1. Field of the Invention
The present invention relates to an automatic MDF apparatus used in an exchange.
2. Description of the Related Art
Recently, compact and light-weight exchanges as well as the high-density mounting of exchanges have been promoted. Along with these trends, the amount of cables connected to an MDF apparatus attached to an exchange has increased more and more. On the other hand, an automatic MDF apparatus in which robots automatically perform wiring or modify the combination of wires, has been invented and put into practical use. According to such an MDF apparatus, for example, every time a new subscriber wants to subscribe to an unattended telephone office, a new wiring and a modification in the combinations of wires can be automatically made.
FIG.1 shows a configuration of a first conventional automatic MDF apparatus.
In the configuration shown in FIG.1, a multi-layered printed wiring board in which wires are embedded horizontally and vertically, and at the points where wires cross, holes are opened, is made a basic unit of one switch. This basic unit of a switch is called a matrix board (MB). In this configuration, a number of matrix boards 121 are arrayed and mounted on both sides of the automatic MDF apparatus, and inside the automatic MDF apparatus robots 123 are provided to insert a pin in the hole of the matrix board 121 for short-circuiting wires. The robot 123 determines the rough position of the point by both a row sensor and a column sensor, and locates the precise position by applying a laser beam to a reference marker provided on the surface of the matrix board 121. When finding a position to insert a pin in this way, the robot 123 inserts the pin in the hole of the matrix board 121.
On the matrix board 121 a wiring pattern is formed, and wires cross with each other at the position of each hole. Therefore, when a pin for short-circuiting the wires is inserted by the robot 123, different wires are connected and a signal route is formed. By changing the position of inserting a pin, the connecting relation between the wires is modified, and a different signal route is formed. In this way, a signal coming from the telephone cable of a subscriber is switched over in the automatic MDF apparatus and inputted to an exchange located in a subsequent stage. In the configuration shown in FIG.1, since matrix boards 121 are provided on both sides of the automatic MDF apparatus, robots 123 inside the automatic MDF apparatus handle the matrix boards on both sides of the automatic MDF apparatus.
Today's MDFs adopt a three-stage switching configuration. If a signal route is switched over by a switch in a first stage, a signal is inputted to a switch in a second stage, and if the route is switched over again by a switch in the second stage, the signal is inputted to a switch in a third stage, and the signal outputted from the switch in the third stage is inputted to an exchange. As described earlier, when a new subscriber is accommodated in an exchange by laying a new piece of cable at the time of a new subscription or a relocation, an MDF is used to appropriately set up the signal route of the new subscriber and to accommodate the subscriber in the exchange. Although the change-over of a wiring route by a robot 123 does not occur so often and a high-speed change-over is not always required to rapidly switch over a wiring route, it is desirable that the change-over speed of the robot 123 is high.
FIG. 2 explains the connecting operation of wiring by inserting a pin in a hole of a matrix board using a robot.
As shown on the right of FIG. 2, wiring is made on the hashed part of the matrix board. Wires are embedded in four layers inside the matrix board. Usually, wires are laid in both x-axis and y-axis directions. At an intersection of the wires in both directions, a hole with a diameter of approximately 1 mm as shown on the left of FIG. 2 is made to cut a connection. Each of the output lines of the wires in the x-axis direction and in the y-axis direction are connected with another board or to an external cable through a connector unit (CN unit).
The left side of FIG. 2 shows how wires embedded in a matrix board are connected by a connection pin inserted by a robot, and is a cross section of the matrix board. As shown in FIG. 2, generally speaking, wires are laid in four layers, which are classified into two groups of A and B wire layers. These A and B wires layers correspond to the upward and downward lines of a telephone circuit. For example, if the A wire is upward line, the B wire is a downward line. The X and Y layers of each of the A and B wires correspond to the wires in the x-axis and y-axis directions shown on the right of FIG. 2. The connection pin is provided with a contact spring in the middle. When the connection pin is inserted in a hole, the X and Y layers are short-circuited, and a signal flows from an X layer to a Y layer or vice versa. Such a contact spring is provided for each of both A and B wire layers, for example, in such a way that if the upward line is connected, the downward line may also be connected simultaneously.
Generally speaking, although the connection pin is made of engineering plastic, the material is not necessarily limited to engineering plastic. The material of the contact spring is not also limited to a specific material, only one that has a sufficient electrical conductivity.
FIG. 3 shows a configuration of a matrix board in a second conventional automatic MDF apparatus.
In the configuration shown in FIG. 3, the size of the automatic MDF apparatus is reduced by locating matrix boards 140-1 through 140-4 and matrix boards 141-1 through 141-4 orthogonally to each other. The matrix boards 140-1 through 140-4 are located in parallel, and robots are provided between the matrix boards 140-1 through 140-4 to make the robots perform a switching work. The matrix boards 141-1 through 141-4 are also located in parallel and robots are provided between them. The matrix boards 140-1 through 140-4 and 141-1 through 141-4 are located orthogonally to each other, and are wired and connected at contacting points 142-1 through 142-4.
When the matrix boards are located in this way, as shown in FIG. 1, space can be used more effectively than when all the matrix boards are located only horizontally, and the volume occupied by the matrix boards can be reduced. As a result, the volume of the automatic MDF apparatus itself can be reduced.
FIG. 4 shows a configuration of a third conventional automatic MDF apparatus.
In the configuration shown in FIG. 4, matrix board units 154 in which a plurality of matrix boards are accommodated, are mounted on shelves, which are accommodated in a frame 150 of an automatic MDF apparatus. A robot 152 is composed of a support member consisting of an elevator 152c and an arm element 152b, and a head element 152a held by this support member. The head element 152a can move back and forth along the arm element 152b, and can also move to an arbitrary position in the matrix board unit 154 in conjunction with the left and right movement of the arm element 152b along the elevator 152c. When the robot is moved to another matrix board unit 154 to perform a switching work, the arm element 152b is moved to either of the left and right ends of the elevator 152c, and then the elevator 152c is moved up and down the frame 150. When the robot 152 comes to the target matrix board unit 154, the arm element 152bis moved laterally to a hole where the switching is to be performed. Such operations are controlled by a control circuit in a control package 160, and the power is supplied by a power supply unit 158.
The connection (link) between the matrix board units 154 is made by providing a connector on the side of each matrix board unit 154 and using a wiring harness, etc.
In the configuration shown in FIG.1, when a large-scale network is configure between the matrix boards of an MDF, both the required number of matrix boards and the number of holes per matrix board increases even if a three-stage switching configuration is adopted. As a result, the mounting area of matrix boards increases, and thereby the external dimensions of an automatic MDF apparatus also increase. Furthermore, when the external dimensions of an automatic MDF apparatus increase, the operation range of a robot also increases, which causes the following problems.
(1) Since the structure of a robot needs to be stiffened, the robot becomes heavy and large.
(2) While positioning in units of several tens of micrometers is required, an operation range of 1 to 2 m is needed, which is incompatible.
(3) When the operation distance to be travelled by a robot in one operation increases, as a result, the operation time also increases.
In the configuration shown in FIG. 3, when a large-scale network is configrued between the matrix boards of an MDF, the number of matrix boards increases. In this configuration, since a plurality of matrix boards 141-1 through 141-4 are connected to one side of each of matrix boards 140-1 through 140-4, the number of the matrix boards 141 increases, the size of each of matrix boards 140 must be increased. However, since the available size of a printed wiring board being the basic material of a matrix board is limited in terms of the production technology, in this configuration, MDFs with such a large-scale network configuration are not actually available. Furthermore, in this case, the location of cables connected to both line and exchange sides is restricted, the cables hinder the removal of robots, and work efficiency deteriorates.
In the configuration shown in FIG. 4, since links are formed using wiring harnesses, the number of links increases, the number of manufacturing processes increases, and when matrix boards are mounted on the apparatus, errors are easy to occur, since there are a lot of connectors between link wiring harnesses and matrix boards. Since an elevator mechanism the robots moves up and down, the mechanism to operate the robots becomes comparatively large, though the robots are small, and it is difficult to speed up the movement.